Refrigeration system and control



Dec. 26, 1961 J. G. LEIMBACH 3,014,351 I REFRIGERATION SYSTEM AND CONTROL Filed March 16, 1960 q 28 INVENTOR- JOHN GEORGE LEIMBACH BY FIG. 2 MWT WM ATTORNEYS United States Patent Office 3,914,351 Patented Dec. 26, 196i 3,014,351 REFRIGERATION SYSTEM AND CONTROL John George Leimbach, Crestwood, Mo., assignor to Sporlau Valve Company, St. Louis, Mo., a corporation of Missouri Filed Mar. 16, 1960, Ser. No. 15,420 12 Claims. (Cl. 62-197) This invention relates generally to improvements in a refrigeration system and control, and more particularly to an improved control device adapted to limit the load on the compressor motor of a refrigeration or cooling system and adapted to cool the refrigerant vapor returning to the compressor. 1

In a cooling system of the compressor-condenser-evapora-tor type, an increase in the ambient temperature surrounding the condenser and evaporator causes an increase in the power consumption of the compressor motor because of an increase both of evaporator pressure and of head pressure.

It is an important objective of the present invention to provide a control device in a system of this type that regulates and limits the power consumption of the compressor motor.

An important object is achieved by the provision of a control device that causes the electrical input to the compressor motor to be held to a predetermined maximum value even under conditions of high heat load.

In many refrigeration systems of this type a thermostatic expansion valve is utilized to regulate the flow of refrigerant to the evaporator, the thermostatic expansion valve being actuated by a thermal sensing bulb located in thermo-responsive relation to the suction line at the evaporator outlet. An important object is to provide a control device that is actuated in response to an increase in head pressure or an increase in evaporator pressure in the system to cause the thermostatic expansion valve to limit flow of refrigerant to the evaporator by affecting the temperature of the thermostatic expansion valve sensing bulb.

When the refrigerant how to the evaporator is limited in such systems, the superheat and temperature of the refrigerant vapor entering the compressor are increased. In some cases, this condition may be harmful to the com pressor motor if it is inside the compressor housing and depends on the temperature of the returning vapor to cool the motor windings.

Another important objective is achieved by the provision of a control device in the system which solves the above discussed potential heat problems by cooling the vapor at the compressor inlet with the addition of expanding refrigerant into the suction line when the vapor temperature at the evaporator outlet is increased above a safe value.

It will be realized that when the vapor temperature at the evaporator outlet is increased, there is a corresponding increase in evaporator pressure and a generally proportionate increase to head. pressure. Another important object is to provide a control device that per-forms the previously explained operation and function in response to an increase in head pressure or an increase in evaporator pressure above predetermined values.

Other important advantages are afforded inthis type of system in that the flow of expanding refrigerant. to the suction line can be increased by the control device so as to cool the vapor in the suction line leading to thecompresscr, in addition to causing a throttling action of the thermostatic expansion valve as discussed.

Yet another important object is achieved by the novel structure of the valve mechanism in the control device and by the provision of the control device as an article of manufacture.

Another important objective is to provide a control device in a refrigeration system that is simple and durable in construction, efiicient in operation, economical to manufacture and assemble, fully automatic in operation and which can be quickly and easily installed.

The foregoing and numerous other objects and ad vantages of the invention will more clearly appear from the following detailed description of a control device and the system in which it is installed, particularly when considered in connection with the accompanying drawing, in which:

FIG. 1 is a diagrammatic view of a refrigeration system utilizing a thermostatic expansion valve and illustrating the installation of the present control device;

FIG. 2 is a cross-sectional view of an embodiment of the control device as seen in a vertical plane, and

FIG. 3 is a fragmentary, diagrammatic view of a modification in the refrigeration system in which the control device is installed.

Referring now by characters of reference to the drawing, and first to FIG. 1, it is seen that the control device is utilized in a refrigeration system of compressor-condenser-evaporator type. More particularly, the refrigeration system includes a compressor 10 driven by an electrical motor 11, the compressor 10 being operatively connected by a line to a condenser 12. A receiver 13 is connected to the outlet of condenser 12 and is connected by a liquid line 14 to the inlet of a thermostatic expansion valve 15. The outlet of thermostatic expansion valve 15 is connected to a conventional refrigerant distributor 16 of pressure type. The distributor 16 feeds refrigerant to a multi-circuit evaporator 17. In this embodiment, the evaporator 17 includes three parallel circuits with one outlet header. The outlet of evaporator 17 is connected by a suction line 18 back to the compressor 10.

The thermostatic expansion valve 15 is of conventional construction and is a unit of this type sold by Sporlan Valve Company of St. Louis, Missouri. This expansion valve 15 has been fully and adequately described in many prior patents owned by this company including US. Patent No. 2,922,292, issued January 26, 1960 and entitled Valve Assembly for a Refrigeration System.

As is usual, the thermostatic expansion valve 15 includes a thermal sensing bulb 20 located in adjacent therrnoresponsive relation to the suction line 18 at the outlet of evaporator 17. The bulb 20 is connected by a capillary tubing 21 to a motor unit generally referred to at 22 of the thermostatic expansion valve 15.

A limited fluid charge is introduced into bulb 2t}, and consists preferably of a fluid having characteristics approaching or identical with those of the refrigerant employed in the system, and will usually consist of dichlorodifioromethane, monochlorodifioromethane, methyl chloride or any other of the refrigerants selected for the system according to the preference and field of usage. Below a predetermined temperature at the bulb 29, the charge is partly in liquid phase and partly in vapor phase; while above this temperature all of this charge is in vapor phase.

The motor unit 22 of the thermostatic expansion valve 15 operates under the influence of fluid pressure changes i occurring by reason of thermal effect imparted to bulb 20 in response to changes in superheat in the suction line 18. Upon a decrease in superheat, the bulb 20 will cause the motor unit 22 to throttle or limit refrigerant flow through the thermostatic expansion valve 15, and hence limits the refrigerant flow to the evaporator 17.

A control device referred to at 23 is placed in this system as disclosed in FIG. 1 in order to limit the load on the compressor motor 11 and, if desired, to cool the refrigerant vapor returning to the compressor 10.

The control device 23 includes a valve 24 that may be H of the construction illustrated in FIG. 2. The valve 24 3 of FIG. 2 includes a body having a chamber 26 formed therein. The body 25 is provided with a valve inlet 27 and a valve outlet 28, both communicating with chamber 26.

A nipple 30 is threadedly attached to the valve body 25 and projects inwardly into chamber 26. The nipple 30 is provided with a valve port 31 that communicates with chamber 26 and with the valve inlet 27. The nipple 3t) constitutes a partition between valve inlet 27 and valve outlet 28.

A valve member 32 is reciprocally mounted in valve chamber 26 and includes a sleeve 33 that slidably receives and interfits the nipple 30. The sleeve 33 includes a plurality of lateral apertures 34 that place the chamber 26 in communication with the valve port 31. A pointed tip attached to valve member 32 is adapted to open and close the valve port 31 upon reciprocation of valve member 32.

A compression spring 35 is located in chamber 26, one end of spring 35 engaging a collar on valve member 32 and the other end engaging the body 25 at the bottom of chamber 26. The spring 35 tends to urge the valve member 32 upwardly toward a valve open position.

The motor unit referred to at 36 is attached by a casing 37 to the top of body 25. A diaphragm 40 constituting a first flexible motor element is attached to and extends across the casing 37, dividing the casing 37 into separate compartments 41 and 42. The bottom side of diaphragm 40 engages the valve member 32, and is held in engagement therewith by the action of spring 35. The compartment 41 is in direct communication with chamber 26.

As will be explained in more detail subsequently, the chamber 26 and hence the lower side of diaphragm 40 is subjected to evaporator pressure.

A cylindrical 'body housing 43 is attached to the top of motor unit casing 37. A plurality of balls 44 (a total of three in the embodiment disclosed) constituting followers are mounted reciprocally in sockets 45 formed in the lower wall of body housing 43. The balls 44 engage the top surface of a follower plate 46 attached to the top of diaphragm 40. Located within the body housing 43 is a collar 47 having an out-turned lower flange 50 that seats on the top of balls 44.

A compression spring 51 encircles the collar 47, one end of spring 51 engaging the collar flange 50 and the opposite end of spring 51 abutting a closure cap 52 that is threadedly connected to the top of body housing 43. The spring 51 tends to urge the balls downwardly into engagement with the follower plate 46, and hence places a constant pressure on the upper side of diaphragm 40 in opposition to the evaporator pressure exerted on the lower side.

Upon threaded adjustment of cap 52, the loading of compression spring 51 can be selectively varied so as to place a predetermined constant pressure on diaphragm 40.

A bellows 53 constituting a second flexible motor element is mounted within the body housing 43, and more particularly is located within the collar 47. The lower end of bellows 53 is fixed to and enclosed by the bottom wall 54 of the housing 43, while the upper end is closed and at times is in contact with the upper end of collar 47. The interior of bellows 53 communicates with fitting 55 through a passage 56 so that the inner side of bellows 53 is subjected to head pressure as will 'be explained subsequently.

Located between the upper end of bellows 53 and a plug 57 that is threadedly attached to cap 52, is a compression spring 6" The spring 60 serves to exert a constant pressure on the outer side of bellows 53. Upon threaded adjustment of plug 57, the pressure or loading of spring 63 on bellows 53 can be adjusted to a predetermined value.

It will be noted that the constant pressure on bellows 53 acts through collar 47, balls 44 and diaphragm 40 in a direction tending to move the valve member 32 toward a closed position. On the other hand, the head pressure exerted on the inner side of bellows 53 acts through the same chain of elements and tends to allow the valve member 32 to move toward an upwardly open position.

Extending upwardly from the bottom wall 54 of valve housing 43 is a stop member 61 located within bellows 53. The end of stop member 61 is adapted to engage the upper end of bellows 53 to limit the collapse of bellows 53 at a predetermined point.

When the valve 24 is connected to the system, as shown in FIG. 1, the inlet 27 is connected to the system ahead of the evaporator, and more particularly to the outlet of the expansion valve 15, by line '52.

The outlet 28 of valve 24 is connected by line 63 to the suction line 18 at the evaporator outlet 17 ahead of the thermal sensing bulb 20.

The fitting S5 of valve 24 is operatively connected to the liquid line 14 by tubing 64. It is seen that the interior of bellows 53 is placed in direct communication with the liquid line 14 through passage 56 and tubing 64. Thus, the interior of bellows 53 is subjected to head pressure.

This control device works in that valve 24 opens, closes or meters refrigerant from its inlet 27 through its outlet 28 as determined by the head pressure and by the evaporator pressure. The operation of this limit control 23 is determined by the setting of spring 51 which balances the upward force of the diaphragm 40 resulting from evaporator pressure exerted on the lower side of such diaphragm. When the evaporator pressure rises above a preset limit, the valve port 31 is opened.

Similarly, the amount of opening of valve port 31 is determined by the setting of spring 60, which balances the upward force of bellows 53 resulting from the head pressure exerted inside of it. Then the head pressure rises, the bellows 53 exerts an upward force tending to open the valve port 31.

In both instances, an increase in either the evaporator pressure or the head pressure above predetermined values will open the valve port 31 and permit flow of refrigerant through valve 24. The flow of refrigerant through valve 24 is partly in liquid and partly in vapor phase as it leaves the point between the expansion valve 15 and the distributor 16 and is further expanded to evaporator pressure when it enters the suction line 18. Thus the referigerant by-passes the evaporator 17 and enters the suction line 18 with no superheat. Therefore, this cold refrigerant, coming in contact with the expansion valve bulb 20 closes or throttles the expansion valve 15 and shuts off or reduces refrigeration flow through the evaporator 17. This will reduce the load on the compressor 10, on the compressor motor 11, and on the condenser 12 and tends to limit this load to a predetermined maximum value. Thus, it is seen that the effect of bellows 53 is to reduce the evaporator pressure when the head pressure rises. The action of the bellows 53 affects the spring pressure on the diaphragm 40 and more particularly lowers the point at which the valve opens.

'When the load falls below the predetermined value, the reverse action takes place and. with the control valve 24 closed, the system functions in a normal manner as determined by the normal operation of the thermostatic expansion valve 15.

It will be noted that every time the control valve 24 opens enough to shut off the expansion valve 15, the supply of refrigerant to the control valve 24 is shut off also. Then the flow of cold refrigerant to suction line 18 ahead of bulb 20 is stopped, the thermostatic expansion valve 15 will again open until the flow of cold refrigerant through the control valve 24 which is automatically resumed, will cause closure of the expansion valve 15 again. Of course, after once being closed, the expansion valve 15 can be again opened if either or both the head pressure and evaporator pressure falls below predetermined values so that the valve port 31 through valve 24 is closed.

In the particular system shown in FIG. 1, at the point where inlet line 62 is connected at the expansion valve outlet, the refrigerant pressure is from to 50 pounds higher than the evaporator outlet pressure, while the cornpressor 10 is operating. It has been found that by connecting the control valve inlet 27 to this point, satisfactory and smooth operation results. This specific location is desirable also because it is seen that the thermostatic expansion valve is closed when the compressor It) stops, and hence refrigerant cannot enter the compressor inle through the load limit control valve 24 during this period.

In addition to limiting the load on the system, this control device 23 can, if desired, introduce liquid refrigerant into the suction line 18 in sulficient quantity to cool the suction vapor so that, during the time the evaporator 17 is being starved, highly superheated vapor does not reach and damage the compressor motor windings. The amount of such cooling of the suction gas can be regulated by the size of the port 31 in the control valve24, by the distance upstream from the bulb 20 that the control valve outlet is located, and by the use of a more or less restricting tube in lieu of line 62 forming the connection between the inlet of the control valve 24 and the expansion valve outlet.

By the use of such a restricting or capillary tube, or by its elimination, or by proper choice of the control valve port 31, or by the relative location of control valve outlet relative to the thermostatic expansion valve bulb 20, a control can be provided which will either merely control the refrigerating load or which will also cool the suction vapor to any reasonable extent, yet without the danger of allowing too much liquid refrigerant to bypass the evaporator 17 into the compressor 10.

The control valve 24 can be operatively connected to the refrigeration system in a slightly different manner as is illustrated by the modification of FIG. 3. The system is exactly the same except that the inlet 27 of control valve 24 is connected by line 65 to the liquid line 14. In this instance, a smaller valve port 31 is required as compared with the size used in the system of FIG. 1 in order to avoid abrupt action and possible hunting of the control valve 24 and of the thermostatic expansion valve 15.

It will be apparent that during the shut-down period in which expansion valve 15'is closed, it might be possible for refrigerant flow to continue through the control valve 24 in the system of FIG. 3. To preclude this possibility, a shut-off valve 66 is connected in line 65 ahead of the control valve 24.

The valve 24 operates in the same manner when operatively connected in the systems of FIG. 1 or FIG. 3. If the evaporator pressure rises above a predetermined value, the evaporator pressure in chamber 26 and exerted on the bottom side of diaphragm 4t) overcomes the constant pressure exerted on the upper side by spring 51 so as to enable the valve member 32 to rise and hence open the valve port 31.

Similarly, upon a rise in head pressure above a predetermined value, the head pressure in the interior and on one side of bellows 53 overcomes the constant pressure exerted on the opposite side by spring 64), and hence causes an extension of bellows 53. Upon such extension, the bellows 53 raises the collar 47 and permits the balls 44, diaphragm 4t) and valve memberSZ to rise and hence open the valve port 31.

As explained previously, adjustment of cap 52 and plug 57 pre-select the loading of springs 51 and 60 respectively andhencedetermine the evaporator pressure and head pressure values at which the valve port 31 will open.

Although the invention has been described by making detailed reference to a control device in different refrigeration systems, such detail is to be understood in an instructive, rather than in any restrictive sense, many variants being possible within the scope of the claims hereunto appended.

I claim as my invention:

1. In a refrigeration system, a compressor, a condenser connected to said compressor, a liquid line leading from said condenser, an evaporator, means in said liquid line for delivering expanded refrigerant to said evaporator, a suction line connecting said evaporator to said compressor, a valve including a body having an inlet and an outlet interconnected by a passage, a valve connecting the line inlet to the system ahead of the evaporator, another line connecting the valve outlet to said suction line, a valve member in said body for controlling flow of refrigerant through said passage, means in said body subjecting the valve member to a predetermined pressure tending to move the valve member toward a closed position, a motor means connected to said valve member, means for subjecting the motor means to head pressure, and means for subjecting the motor means to evaporation pressure, the motor means acting in response to either a predetermined head pressure or a predetermined evaporator pressure =to open said valve for feeding expanded refrigerant to the suction line.

2. In a refrigeration system, a compressor, a condenser connected to said compressor, a liquid line leading from said condenser, an evaporator, means in said liquid line for delivering expanded refrigerant to said evaporator, a suction line connecting said evaporator to said compressor, a valve including a body having an inlet and an outlet interconnected by a passage, a line connecting the valve inlet to the system ahead of the evaporator, another line connecting the valve outlet to said suction line, a valve member in said body for controlling flow of refrigerant through said passage, means in said body subjecting the valve member to a predetermined pressure tending to move the valve member toward a closed position, a first motor means operatively connected to said valve member, means in said body subjecting the first motor means to evaporator pressure so that said first motor means actuates said valve member in response to a predetermined evaporator pressure to open said valve, and a second motor means operatively connected to said valve member, and means subjecting the second motor means to head pressure so that said second motor means actuates said valve member in response to a predetermined head pressure to open said valve.

3. In a refrigeration system, a compressor, a condenser connected to said compressor, a liquid line leading from said condenser, an evaporator, means in said liquid line for delivering expanded refrigerant to said evaporator, a suction line connecting said evaporator to said compressor, a valve including a body having an inlet and an outlet interconnected by a passage, a line connecting the valve inlet to the system ahead of the evaporator, another line connecting the valve outlet to said suction line, a partition across said passage provided with a valve port, a valve member for opening and closing said port, a first flexible motor element operatively connected to said valve member, means placing a predetermined constant pressure on one side of said first flexible motor element tending to move the valve member toward a closed position, means placing the other side of said first flexible motor element in communication with said passage on the outlet side of said valve port and hence subject to evaporator pressure tending to move the valve member toward an open position, a second flexible motor element operatively connected to said valve member, means placing a predetermined constant pressure on one side of said second flex ible motor element-tending to move the valve member toward a closed position, means placing the other side of said second flexible motor element in communication with the liquid line and hence subject to' head pressure tending to move the valve member toward an open position, the first and second flexible motor elements causing the valve member to open said port upon being subjected respectively to a predetermined evaporator pressure or a predetermined head pressure.

4. In a refrigeration system, a compressor, a condenser connected to said compressor, a liquid line leading from said condenser, an evaporator, a thermostatic expansion valve connected to said liquid line and evaporator for delivering expanded refrigerant to said evaporator, a suction line connecting the evaporator to said compressor, the expansion valve having a thermal sensing bulb adjacent the suction line at the outlet of said evaporator, a valve including a body having an inlet and an outlet interconnected by a passage, a line connecting the valve inlet to the system at the outlet of said expansion valve, another line connecting the valve outlet to said suction line ahead of said bulb, a valve member in said body for controlling flow of refrigerant through said passage, means in said body subjecting the valve member to a predetermined pressure tending to move the valve member toward a closed position, a first motor means operatively connected to said valve member, means in said body subjecting the first motor means to evaporator pressure so that said first motor means actuates said valve member in response to a predetermined evaporator pressure to open said valve, and a second motor means operatively connected to said valve member, and means subjecting the second motor means to head pressure so that said second motor means actuates said valve member in response to a predetermined head pressure to open said valve.

5. In a refrigeration system, a compressor, a condenser connected to said compressor, a liquid line leading from said condenser, an evaporator, a thermostatic expansion valve connected to said liquid line and evaporator for delivering expanded refrigerant to said evaporator, a suction line connecting the evaporator to said compressor, the expansion valve having a thermal sensing bulb adjacent the suction line at the outlet of said evaporator, a valve including a body having an inlet and an outlet interconnected by a passage, a line connecting the valve inlet to the system at the outlet of said expansion valve, another line connecting the valve outlet to said suction line, a partition across said passage provided with a valve port, a valve member for opening and closing said port, a first flexible motor element operatively connected to said valve member, means placing a predetermined constant pressure on one side of said first flexible motor element tending to move the valve member toward a closed position, means placing the other side of said first flexible motor element in communication with said passage on the outlet side of said valve port and hence sub ect to evaporator pressure tending to move the valve member toward an open position, a second flexible motor element operatively connected to said valve member,

means placing a predetermined constant pressure on one side of said second flexible motor element, means placing the other side of said second flexible motor element in communication with the liquid line and hence subject to head pressure tending to move the valve member toward an open position, the first and second flexible motor elements causing the valve member to open said port upon being subjected respectively to a predetermined evaporator pressure or predetermined head pressure for feeding expanded refrigerant to the suction line to cool the bulb so as to limit flow through the expansion valve. I

6. In a refrigeration system, a compressor, a condenser connected to said compressor, a liquid line leading from said condenser, an evaporator, a thermostatic expansion valve connected to said liquid line and evaporator for delivering expanded refrigerant to said evaporator, said expansion valve having a thermal sensing bulb adjacent the suction line at the outlet of said evaporator, a valve including a body having an inlet and an outlet interconnected by a passage, a line connecting the valve inlet to the liquid line ahead of said expansion valve, a shutofl valve in the line interconnecting the valve inlet to the liquid line for selectively opening and closing such line, another line connecting the valve outlet to said suction line, a valve member in said body for controlling flow of refrigerant through said passage, a first motor means operatively connected to said valve member, means in said body subjecting the first motor means to evaporator pressure so that said first motor means actuates said valve member in response to a predetermined evaporator pressure to open said valve, and a second motor means operatively connected to said valve member, and means subjecting the second motor means to head pressure so that said second motor means actuates said valve member in response to a predetermined head pressure to open said valve.

7. In a refrigeration system of compressor-condenserevaporator type, a valve having a body provided with an inlet and an outlet interconnected by a passage, a valve member in said body for controlling flow of refrigerant through said passage, a first flexible motor element operatively connected to said valve member, means subjecting one side of said first flexible motor element to a constant pressure, means subjecting the other side of said first flexible motor element to evaporator pressure, a second flexible motor element in said body operatively connected to said valve member, means subjecting one side of said second flexible motor element to a constant pressure, means subjecting the other side of said second flexible motor element to head pressure, said flexible motor elements tending to move the valve member to an open position when subjected respectively to a predetermined evaporator or a predetermined head pressure.

8. In a refrigeration system of compressor-condenserevaporator type, a valve having a body provided with an inlet and an outlet interconnected by a passage, a valve member in said body for controlling refrigerant flow through said passage, a first flexible motor element operatively connected to said valve member, means subjecting one side of said first flexible motor element to a constant pressure, a line connected to the valve inlet and connected to the system ahead'of the evaporator, means subjecting the other side of said first flexible motor element to evaporator pressure, a line connected to said valve outlet and connected to the suction line of the system, a second flexible motor element in said body operatively connected to said valve member, means subjecting one side of said second flexible motor element to a constant pressure, means subjecting the other side of said second flexible motor element to head pressure, said flexible motor elements tending to move the valve member to an open position when subjected respectively to a predetermined evaporator pressure or a predetermined head pressure.

9. A control device for a refrigeration system of compressor-condenser-evaporator type, comprising a valve having a body provided with a chamber, a partition in said chamber between said inlet and outlet provided with a valve port, a valve member for opening and closing said port, a line connected to the valve inlet and adapted to be connected to the system ahead of the evaporator, a line connected to said valve outlet and adapted to be connected to the suction line of the system, a first flexible motor element extending across said chamber on the outlet side of said valve port adapted to have one side subjected to evaporator pressure, said first flexible motor element being operatively connected to said valve member, a spring in said body operatively connected to the first flexible motor element for exerting a constant pressure on the other side of said first flexible motor element, means for adjusting the loading of said spring so that said evaporator pressure acting through said first flexible motor element causes the valve member to open said port at a predetermined evaporator pressure, a second flexible motor element in said body operativelyconnected to said valve member through the first flexible motor element, means for subjecting the one side of said second flexible motor element to head pressure a spring connected to said second flexible motor element for exerting a constant pressure on the other side of said second flexible motor element, and means for adjusting the loading of the last said spring so that said head pressure acting through said flexible motor elements causes the valve member to open said port at a predetermined head pressure.

10. A control device for a refrigeration system of compressor-condenser-evaporator type, comprising a valve having a body provided with a chamber, said body being provided with an inlet and an outlet to said chamber, a partition in said chamber between said inlet and outlet provided with a valve port, a valve member for opening and closing said port, a first flexible motor element extending across said chamber on the outlet side of said valve port adapted to have one side subjected to evaporator pressure, said valve member being operatively connected to the side of said first flexible motor element subjected to the evaporator pressure, a spring operatively connected to the other side of said first flexible motor element, a cap adjustably connected to said body and engaging said spring for adjusting the load of said spring on said first flexible motor element to place a predetermined constant pressure on said first flexible motor element, in opposition to said evaporator pressure, a second flexible motor element in said body on the other side of said first flexible motor element, means for subjecting one side of said second flexible motor element to head pressure, means connecting the said second flexible motor element to the said other side of said first flexible motor element, a spring operatively connected to said second flexible motor element, a plug engaging the last said spring for adjusting the loading of the spring to place a predetermined constant pressure on the said other side of said second flexible motor element in opposition to said head pressure, said flexible motor elements tending to move the valve member to an open position when subjected respectively to a predetermined evaporator pressure or a predetermined head pressure.

l"-1. A control device for a refrigeration system of compressor-condenser-evaporator type, comprising a valve having a body provided with a chamber, said body being provided with an inlet and an outlet to said chamber, a partition in said chamber between said inlet and outlet provided with a valve port, a valve member for opening and closing said port, a first flexible motor element extending across said chamber on the outlet side of said valve port adapted to have one side subjected to evaporator pressure, said valve member being operatively connected to the side of said first flexible motor element subjected to the evaporator pressure, means in said body operatively connected to the first flexible motor element for subjecting a constant pressure on the other side of said first flexible motor element, a second flexible motor element in said body on the side of the first flexible motor element opposite the valve member, means for subjecting one side of said second flexible motor element to head pressure, reciprocating followers mounted in said body and engaging the first flexible motor element, a collar seating on said followers and attached to said second flexible motor element for movement therewith, means subjecting the other side of said second motor element to a constant pressure, said second motor element acting through the collar and followers to the first flexible motor element for actuation of said valve member, said flexible motor elements tending to move the valve member to an open position when subjected respectively to a predetermined evaporator pressure or a predetermined head pressure.

12. A control device for a refrigeration system of compressor-condenser-evaporator type, comprising a valve having a body provided with a chamber, said body being provided with an inlet and outlet to said chamber, a partition in said chamber between said inlet and outlet provided with a valve port, a valve member for opening and closing said port, a first flexible motor element extending across said chamber on the outlet side of said valve port adapted to have one side subjected to evaporator pressure, the valve member being operatively connected to the side of said first flexible motor element subjected to the evaporator pressure, a plurality of followers reciprocally mounted in said body and engaging the other side of said first flexible motor element, a second flexible motor element in the body on the side of the first flexible motor element opposite the valve member, means subjecting one side of said second flexible motor element to head pressure, a collar attached to said second flexible motor element and seating on said followers, a spring seating on said collar and exerting a constant pressure through said followers to the said other side of said first flexible motor element, a cap adjustably connected to the body and engaging the spring for adjusting the loading of the spring so that said first flexible motor element will cause the valve member to open said port at a predetermined evaporator pressure, another spring engaging the second flexible motor element and subjecting the other side of said second flexible motor element to a constant pressure, and a plug adjustably connected to said cap and engaging said second spring for adjusting the loading of such spring so that said valve member will open said valve port at a predetermined head pressure.

References Cited in the file of this patent UNITED STATES PATENTS 

